The mission of the PSl: Biology-Materials Repository (MR) is to archive, maintain and distribute the protein expression plasmids and annotations created by PSI: Biology. The MR developed an informatics and sample processing pipeline to track, sequence analyze, and annotate each deposited plasmid. Plasmid annotations, which include the full length sequence, vector information, and associated publications, are stored in the freely available, searchable database DNASU (http://dnasu.asu.edu). Plasmids link to external resources, including the PSl Structural Biology Knowledgebase, which facilitates cross-referencing plasmids to additional protein annotations and experimental data. To simplify plasmid distribution, the MR invented an Expedited MTA network, where researchers from network institutions can order and receive PSl plasmids without any institutional delays. The MR has also broadened awareness of the PSl and the MR through community outreach to the general biological community. Currently nearly 34,000 PSl plasmids and 75 empty vectors are available upon request from DNASU (http://dnasu.asu.edu). As the PSl transitions to PSL Biology, the MR will co-evolve to improve many of its current activities and to better represent the biological focus of the PSl program. In particular, the MR will (1) Continue collecting, processing, validating, archiving and maintaining plasmids created by PSL Biology to function as a centralized resource for biologists to access PSl plasmids. (2) Improve the user experience with improved interfaces for depositing, analyzing, validating, retrieving, and annotating PSL Biology plasmids. (3) Accelerate biological discovery through increased distribution of PSL Biology plasmids. Overall, the MR's repository of expression-ready plasmids allows the research community to dissect the biological function of proteins whose structures have been identified by the PSl. With the added biological focus in PSI: Biology, the distribution of these materials will help researchers expand the knowledge of the role of proteins both in normal biological processes and in disease. RELEVANCE (See instructions): In determining the 3D shapes of important proteins, PSI: Biology researchers create tools called plasmids that can be used by others to study the functions of those proteins in health and disease. The Materials Repository collects these plasmids, verifies that they are correct, and shares them with researchers worldwide. Sharing these plasmids will improve understanding of disease, its diagnosis and its treatment.